The present invention relates to improvements in sanding tools and more particularly to a cylindrical sanding device suitable for use on curved and irregular surfaces and capable of being mounted in a drill or tool chuck.
Sanding devices currently in use pose several problems. First, by its very nature, sandpaper wears down very quickly thus requiring an operator to replace it at frequent intervals. Even where the sandpaper is not yet worn out, it is often necessary to switch from a coarse to a fine grade of paper in order to complete a job properly. Because of this necessity for frequent replacement of sandpaper, it is highly desirable that a sanding device be easily loaded and unloaded. At the same time however, the strong tangential forces which act upon an abrasive rotating head require that the paper be held securely.
In order to obtain a secure hold, the devices disclosed in the prior art have required special attaching means which have added a great deal to their cost of production while making the process of loading and unloading abrasive paper much more difficult. For example, the cylindrical sanding head of the device disclosed in U.S. Pat. No. 3,774,354 requires a screw to hold the abrasive paper strip in place. More specifically, the insertion of a screw through one side of the cylinder forces a central mandrel against the other side thereby effecting a hold on a strip of abrasive paper located therebetween.
Likewise, the device described in U.S. Pat. No. 1,319,417 requires a pair of radially opposed arms to hold the abrasive strip securely onto the cylindrical sanding head. The arms are forced against the strip by a threaded rotating sleeve means attached to the end of the cylinder.
Finally, in order to securely hold the abrasive strip on the cylindrical sanding head disclosed in U.S. Pat. No. 4,067,149, the strip must have an adhesive backing. An end of this strip is inserted into a longitudinally extending slot in the cylindrical head. Although achieving a strong hold, this arrangement makes it difficult to switch back and forth between different grades of sandpaper.
An alternative type of sanding device which securely holds the sandpaper and permits easy replacement of the spent paper is disclosed in U.S. Pat. Nos. 2,174,945 and 2,366,158. In these devices, a roll of paper is mounted on a mandrel internal to the cylindrical head tube. One end of the paper is attached to the mandrel and the other end is guided through a slot disposed longitudinally along the tube. When the paper outside the circumference of the tube becomes worn out, it is simply torn off and replaced by paper from the roll. The problem with these devices however is that a considerable effort is required to replace one kind of paper with another kind. Thus, an operator who desires to switch from a rough to a finer grade of paper must disassemble nearly the entire device to do so.